1. Field of Technology
The embodiments herein relate generally to protecting battery cells. More specifically, the embodiments herein relate to using thermal shields to prevent thermal runaway events.
2. Description of the Related Art
Electric vehicles require high energy density rechargable batteries in order to have performance and range comparable to internal combustion engine (ICE) vehicles. This usually requires individual battery cells to be packed in a tight configuration. However, rechargeable batteries have the potential to experience thermal runaway, resulting in a dangerous situation when packed tightly together. Thermal runaway can be caused by external or internal stimuli. External stimuli may include elevated temperatures or physical puncturing of the cell. Internal stimuli may include manufacturing defects (such as some kind of conductive debris) or lithium plating/dendrite formation between electrodes (usually tied to over discharge or abuse during charging). Under such failure, a common rechargeable lithium ion cell can reach temperatures in excess of 700 degrees Celsius and release hot gas and flame (i.e., cause fire). If this battery is part of a multi-cell “pack,” neighboring cells and surrounding materials absorb the generated heat. A neighboring second cell may overheat and also go into thermal runaway following the first cell, creating a dangerous chain reaction. The gas released by a cell in runaway also has the potential to melt the crimp seals of neighboring cells. The crimp seal separates the positive and negative cell terminals, and a melted crimp seal would cause the cell to short circuit and also experience thermal runaway.
Current battery pack designs combine insulators and heat spreading mechanisms to manage heat flow safely. However, the crimp seals of neighboring cells are still vulnerable to being melted by hot vented gas. Therefore, there is a need for a device and method to protect the neighboring cells from hot vented gas.